检索结果-内蒙古大学图书馆

Method for estimating the central frequency of phase-coded radar signals

IET SIGNAL PROCESSING 2016年第9期10卷 1073-1081页

作者： Yildirim, Alper TUBITAK BILGEM ILTAREN Ankara Turkey

The authors analyse radar carrier frequency estimation errors in digital electronic support measures receivers. They assume that the received signal is phase-coded, real-valued and embedded in white Gaussian noise. The corresponding Cramer-Rao lower bound (CRLB) for the frequency estimation is derived and formulated. The performance degradation can be significant when just a single traditional fast fourier transform (FFT) algorithm used to estimate the central frequency of a phase-coded signal, where the spectrum is wide and distributes across many frequency bins. In this study, they assume that the FFT magnitude response of the received signal can be approximated by a raised Gaussian-shaped function. The corresponding Gaussian function fitting (GFF) estimator is proposed as a peak frequency estimation technique. Typical FFT-based frequency estimation process is simulated and the performance of the GFF estimator is compared with that of the most commonly used peak estimators: namely, with the maximum point (MAX) and the spline interpolation (INT). GFF estimator performance is also compared with a K-means-based peak estimator. With extensive set of simulations for different code lengths, they demonstrate that the proposed technique significantly reduces carrier (central) frequency estimation errors while illustrating CRLB within the figure.

关键词： frequency estimation radar signal processing phase coding Gaussian noise white noise fast fourier transforms Gaussian processes interpolation central frequency estimation method phase-coded radar signals radar carrier frequency estimation error analysis digital electronic receivers white Gaussian noise Cramer-Rao lower bound CRLB performance degradation fast fourier transform algorithm frequency bins raised Gaussian-shaped function peak frequency estimation technique FFT-based frequency estimation process GFF estimator spline interpolation maximum point K-means-based peak estimator Gaussian function fitting estimator

来源：评论

学校读者我要写书评

暂无评论

Application of MEMS Accelerometer for Detection and Diagnosis of Multiple Faults in the Roller Element Bearings of Three Phase Induction Motor

引用

IEEE SENSORS JOURNAL 2016年第1期16卷 145-152页

作者： Maruthi, G. S. Hegde, Vishwanath Smt LV Govt Polytech Dept Elect & Elect Engn Hassan 573201 India Malnad Coll Engn Dept Elect & Elect Engn Hassan 573202 India VTU Belagavi Karnataka India

This paper presents a simple, non-electrical contact approach to detect and analyze multiple faults in the roller element bearings of three phase induction motor by vibration analysis using microelectromechanical systems (MEMS) accelerometer. The ability of the proposed method has been investigated experimentally under no load, single phase and unbalanced voltage conditions. The frequency analysis of motor vibration due to bearing fault has been carried out by fast fourier transform algorithm. The appearance of fault frequencies in vibration spectrum will indicate multiple faults in the bearings and also the existence of side-band frequency components around fundamental frequency component indicates air gap modulation due to bearing fault. Experimentally obtained fault frequencies are compared with analytical values and found that both are closely matching. This indicates that the proposed method can be reliably employed to detect from simple to complex faults in the bearings of induction motor using MEMS accelerometers.

关键词： fast fourier transform algorithm MEMS accelerometer multiple faults single phase condition unbalance voltage vibration signature analysis

来源：评论

学校读者我要写书评

暂无评论

Versatile algorithms for the computation of 2-point spatial correlations in quantifying material structure

引用

INTEGRATING MATERIALS AND MANUFACTURING INNOVATION 2016年第1期5卷 1-15页

作者： Cecen, Ahmet fast, Tony Kalidindi, Surya R. Georgia Inst Technol Sch Computat Sci & Engn Atlanta GA 30332 USA Georgia Inst Technol George W Woodruff Sch Mech Engn Atlanta GA 30332 USA

This paper presents a generalized framework along with the associated computational strategies for a rigorous quantification of the material structure in a range of different applications using the framework of 2-point spatial correlations. In particular, we focus on applications requiring different assumptions about the periodicity and/or involving irregular domain shapes and potentially extremely large datasets. Important details of the computational algorithms needed to address these challenges are developed and illustrated with example case studies. algorithms developed and presented in this work are available at http://***/10.5281/zenodo.31329.

关键词： fast fourier transform algorithm Irregular Domain Microstructure Domain Rigorous Quantification Spatial Correlation

来源：评论

学校读者我要写书评

暂无评论

Simulation domain size requirements for elastic response of 3D polycrystalline materials

引用

MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING 2016年第1期24卷 015006-015006页

作者： Ozturk, Tugce Stein, Clayton Pokharel, Reeju Hefferan, Christopher Tucker, Harris Jha, Sushant John, Reji Lebensohn, Ricardo A. Kenesei, Peter Suter, Robert M. Rollett, Anthony D. Carnegie Mellon Univ Dept Mat Sci & Engn 5000 Forbes Ave Pittsburgh PA 15213 USA Los Alamos Natl Lab Div Mat Sci & Technol POB 1663 Los Alamos NM 87544 USA Carnegie Mellon Univ Dept Phys 5000 Forbes Ave Pittsburgh PA 15213 USA RJ Lee Grp 350 Hochberg Rd Monroeville PA 15146 USA Universal Technol Corp Dayton OH 45432 USA Mat & Mfg Directorate Air Force Res Lab Wright Patterson AFB OH 45433 USA Argonne Natl Lab Adv Photon Source 9700 South Cass Ave Lemont IL 60439 USA

A fast fourier transform (FFT) based spectral algorithm is used to compute the full field mechanical response of polycrystalline microstructures. The field distributions in a specific region are used to determine the sensitivity of the method to the number of surrounding grains through quantification of the divergence of the field values from the largest simulation domain, as successively smaller surrounding volumes are included in the simulation. The analysis considers a mapped 3D structure where the location of interest is taken to be a particular pair of surface grains that enclose a small fatigue crack, and synthetically created statistically representative microstructures to further investigate the effect of anisotropy, loading condition, loading direction, and texture. The synthetic structures are generated via DREAM3D and the measured material is a cyclically loaded, Ni-based, low solvus high refractory (LSHR) superalloy that was characterized via 3D high energy x-ray diffraction microscopy (HEDM). Point-wise comparison of distributions in the grain pairs shows that, in order to obtain a Pearson correlation coefficient larger than 99%, the domain must extend to at least the third nearest neighbor. For an elastic FFT calculation, the stress-strain distributions are not sensitive to the shape of the domain. The main result is that convergence can be specified in terms of the number of grains surrounding a region of interest.

关键词： spectral full-field modeling fast fourier transform algorithm anisotropic elastic response microstructures high-energy x-ray diffraction microscopy representative volume element

来源：评论

学校读者我要写书评

暂无评论

Electromagnetic field radiated in air from a horizontal/vertical magnetic dipole in sea

引用

JOURNAL OF ELECTROMAGNETIC WAVES AND APPLICATIONS 2015年第7期29卷 858-873页

作者： Wang, Honglei Yang, Kunde Zheng, Kun Northwestern Polytech Univ Sch Marine Sci & Technol Xian 710072 Peoples R China

The propagation characteristics of electromagnetic (EM) waves across the seawater-air interface influence seawater to air communication. The type of underwater antenna determines EM wave propagation performance. However, studies rarely compared the performance of horizontal and vertical magnetic dipoles (HMD and VMD). In this study, the EM fields in air due to HMD/VMD immersed in sea were derived to provide a basis for selecting a suitable underwater antenna for EM wave propagation in undersea-air communication. Analytic results were obtained from the model of a three-layered conducting media. Associated expressions in air were numerically calculated using the fast fourier transform algorithm to present the propagation curves and the distribution patterns of the EM fields. A proof of concept measurement system was constructed, and sea experiments were conducted and compared with theoretical studies. The maximum transmitting-receiving distance in the experiment was achieved by the HMD. The theoretical and experimental results indicate that the HMD antenna is superior to the VMD antenna and that the suggested band of EM wave is feasible for transmission across the seawater-air interface.

关键词： fast fourier transform algorithm layered conducting media underwater loop antenna magnetic dipole

来源：评论

学校读者我要写书评

暂无评论

Online fuzzy time series analysis based on entropy discretization and a fast fourier transform

引用

APPLIED SOFT COMPUTING 2014年第partb期14卷 156-166页

作者： Chen, Mu-Yen Chen, Bo-Tsuen Natl Taichung Univ Sci & Technol Dept Informat Management Taichung 404 Taiwan

Fuzzy time series analysis has been used successfully for forecasting in various domains including stock performance, academic enrollment, temperature, and traffic patterns. Research in this field has concentrated primarily on two issues: the reasonable partition of discourse, and defuzzification methods for discrete datasets. Both issues have a huge impact on the prediction performance of forecasting models. This paper integrates the entropy discretization technique with a fast fourier transform (FFT) algorithm to develop a novel fuzzy time series forecasting model to resolve these issues. The Taiwan Stock Exchange Capitalization Weighted Stock Index (TAIEX) and Dow-Jones Industrial Average (DJIA) financial datasets were used to evaluate the model's performance. The results demonstrate that the presented model is a major improvement over previous fuzzy time series models produced by Chen (1996), Yu (2005), Chang et al. (2011), and Hsieh et al. (2011), and five other conventional time series models. The proposed model is implemented using the bootstrapping method, after which it incrementally updates its prediction capability. Results show that the proposed model's incremental learning mechanism allows it to effectively handle large online financial datasets. (C) 2013 Elsevier B. V. All rights reserved.

关键词： Fuzzy time series Entropy-based discretization fast fourier transform algorithm

来源：评论

学校读者我要写书评

暂无评论

Nonparametric Estimation of the Finite-Time Survival Probability with Zero Initial Capital in the Classical Risk Model

引用

METHODOLOGY AND COMPUTING IN APPLIED PROBABILITY 2012年第4期14卷 919-936页

作者： Qin, Li Pitts, Susan M. Univ Cambridge Stat Lab Ctr Math Sci Cambridge CB3 0WB England

In a classical risk model with zero initial capital and unknown claim-size distribution, we consider the statistical problem of estimating uniformly in t the (unknown) finite-time survival probability phi (0)(t) at time t, given a sample of claim sizes. We construct an empirical estimator of the function phi (0)(center dot) based on the sample of claim sizes, and using a functional approach we establish asymptotic statistical properties of our estimator with respect to supremum norm. We also consider numerical evaluation of finite-time survival probabilities and their empirical counterparts using the fast fourier transform algorithm, and we carry out small-scale simulation studies of the behaviour of our estimator.

关键词： Finite-time survival probabilities Ruin time Functional central limit theorem Infinite-dimensional delta method Empirical processes fast fourier transform algorithm

来源：评论

学校读者我要写书评

暂无评论

Error Compensation Method of Harmonic Analysis for Time Grating Sensor

Error Compensation Method of Harmonic Analysis for Time Grat...

引用

2nd International Conference on Frontiers of Manufacturing and Design Science (ICFMD 2011)

作者： Chen, Ziran Peng, Donglin Zheng, Yong Zheng, Fangyan Zhang, Tianheng Hefei Univ Technol Sch Instrumentat Sci & Optoelect Engn 193 Tunxi Rd Hefei Peoples R China Chongqing Univ Technol Engn Res Ctr Mech Testing Technol & Equipment Minist Educ Chongqing Peoples R China

ISBN: (纸本)9783037852828

Due to the complexity of measurement system, it is hard correct errors by using traditional error separation and error tracing technology. To reduce the production cost and improve the measurement accuracy, a novel error compensation method based on harmonic analysis is presented in this paper. In this way, high precision time grating sensors can be manufactured with low precision mechanical machining method. The experiment results prove that errors can be reduce within +/- 2 ''.

关键词： Harmonic analysis method time grating displacement sensor error compensation fast fourier transform algorithm

来源：评论

学校读者我要写书评

暂无评论

Estimation of local stresses and elastic properties of a mortar sample by FFT computation of fields on a 3D image

引用

CEMENT AND CONCRETE RESEARCH 2011年第5期41卷 542-556页

作者： Escoda, J. Willot, F. Jeulin, D. Sanahuja, J. Toulemonde, C. Mines Paristech Ctr Morphol Math Math & Syst Fontainebleau France Elect France Dept Mat & Mecan Composants Moret Sur Loing France

This study concerns the prediction of the elastic properties of a 3D mortar image, obtained by microtomography, using a combined image segmentation and numerical homogenization approach. The microstructure is obtained by segmentation of the 3D image into aggregates, voids and cement paste. Fullfields computations of the elastic response of mortar are undertaken using the fast fourier transform method. Emphasis is made on highly-contrasted properties between aggregates and matrix, to anticipate needs for creep or damage computation. The representative volume element, i.e. the volume size necessary to compute the effective properties with a prescribed accuracy, is given. Overall, the volumes used in this work were sufficient to estimate the effective response of mortar with a precision of 5%, n and 10% for contrast ratios of 100, 1000 and 10,000, resp. Finally, a statistical and local characterization of the component of the stress field parallel to the applied loading is carried out. (C) 2011 Elsevier Ltd. All rights reserved.

关键词： Microstructure Elastic moduli fast fourier transform algorithm Image analysis Mortar

来源：评论

学校读者我要写书评

暂无评论

Efficient Arithmetic Sum-of-Product (SOP) based Multiple Constant Multiplication (MCM) for FFT

Efficient Arithmetic Sum-of-Product (SOP) based Multiple Con...

引用

IEEE and ACM International Conference on Computer-Aided Design

作者： Karkala, Vinay Wanstrath, Joseph Lacour, Travis Khatri, Sunil P. Texas A&M Univ Dept ECE College Stn TX 77843 USA Rose Hulman Inst Technol Dept ECE Terre Haute IN 47803 USA

ISBN: (纸本)9781424481927

In this paper, we present an arithmetic sum-of-products (SOP) based realization of the general Multiple Constant Multiplication (MCM) algorithm. We also propose an enhanced SOP based algorithm, which uses Partial Max-SAT (PMSAT) to further optimize the SOP. The enhanced algorithm attempts to reduce the number of rows (partial products) of the SOP, by i) shifting coefficients to realize other coefficients when possible, ii) exploring multiple implementations of each coefficient using a Minimal Signed Digit (MSD) format and iii) exploiting the mutual exclusiveness within certain groups of partial products. Hardware implementations of the fast fourier transform (FFT) algorithm require the incoming data to be multiplied by one of several constant coefficients. We test/validate it for FFT, which is an important problem. We compare our SOP-based architectures with the best existing implementation of MCM for FFT (which utilizes a cascade of adders), and show that our approaches show a significant improvement in area and delay. Our architecture was synthesized using 65nm technology libraries.

关键词： FFT algorithm MCM algorithm MSD format PMSAT SOP-based architectures arithmetic sum-of-product computability digital arithmetic fast fourier transform algorithm fast fourier transforms hardware implementations minimal signed digit format multiple constant multiplication partial max-SAT

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：